Electron microscopy provides significant advantages over optical microscopy, such as higher resolution and greater depth of focus. In a scanning electron microscope (SEM) a primary electron beam is focused to a fine spot that scans the surface to be observed. Secondary electrons are emitted from the surface as it is impacted by the primary beam and some electrons from the primary beam are backscattered. The secondary or backscattered electrons are detected and an image is formed, with the brightness at each point of the image being determined by the number of electrons detected when the beam impacts a corresponding spot on the surface.
Electron microscopes are typically large, complex, and expensive instruments that require skilled technicians to operate them. SEM devices typically cost well over $100,000 and require special facilities, including dedicated electrical wiring for power and venting of the vacuum pump outside of the operator area. Further, it can be difficult in a high magnification image such as that of an SEM for a user to determine where on the sample an image is being obtained and to understand the relationship between that image and the rest of the sample.
Because of the SEM's inherent complexity of operation, SEM operators are typically specially trained technicians with technical degrees. The cost of electron microscopes and the sophistication required to operate them have limited their use to research and industry with the resources to obtain this technology and to provide trained operators. With regard to the necessity of trained operators in particular, a more user-friendly interface would allow users with little or no expertise in the operation of SEM devices to take more advantage of such technology.